Methods for determining a combustion chamber pressure of an internal combustion engine are known. Combustion chamber pressure sensors, which measure the combustion chamber pressure in a cylinder of the internal combustion engine and output a corresponding measuring signal may be used for this purpose, for example. However, the signals of the combustion chamber pressure sensors are error prone. If these errors are not corrected, they corrupt the cylinder pressure characteristics calculated from the measured combustion chamber pressure values and, when these cylinder pressure characteristics are adjusted, result in wrong absolute values and thus in a possible imbalance among the cylinders of the internal combustion engine. Different cylinder pressure characteristics, such as an indicated combustion chamber mean pressure or certain conversion points of the heating curve, may be calculated from the combustion chamber pressure curve. A cylinder-individual regulation may be based on these cylinder pressure characteristics. By regulating the indicated combustion chamber mean pressure of the cylinders, for example, it is possible to achieve a more accurate adjustment of the setpoint torques and better balancing of the cylinders in all operating ranges.
For correcting an offset of a combustion chamber pressure sensor or a cylinder pressure sensor, European Published Patent Application No. 0411 580 describes a method for determining cylinder pressure values during an intake stroke of a cylinder and comparing them with a predefined reference minimum value. The differences between the determined cylinder pressure values and the predefined reference minimum value are then used as offset correction values.